Variability studies in F₆ generation recombinant lines of G. Hirsutum X G. Barbadense cross

Atotal of 169, F₆ generation lines of cross between Gossypium hirsutum L. var. DS-28 and G. barbadense L. var. SBYF-425 were evaluated. About 52.66% genotypes had morphological characters of female parent, 15% intermediate character of petal spot and 10% showed male parent characters. Seed cotton yield ranged from 6.63 kg/ha to 4429.12 kg/ha with 74.81% genotypic coefficient of variation (GCV), 95% heritability and 149.93% genetic advance as percent of mean (GAM). Photosynthetic rate varied from 6.27 to 25.5 μmol CO₂ m⁻² sec⁻¹ with 52.74% GCV, 93% heritability and 104.62% GAM. Fibre strength was within the range of 18.53 to 28.08 g/tex with 8.76% GCV, 100% heritability and 18.37 GAM. The values for fibre length ranged from 22.65 to 35.90 mm with 8.76% GCV, 81% heritability and 16.19 GAM. Genotypes HBS-2, 13, 20, 142, 158, 170 and 181 were significantly superior over DS-28 (1098 kg/ha, 21.11 g/tex) for seed cotton yield and fibre strength. These selections recorded 55 to 135 per cent yield increase over DS-28. Similarly genotypes HBS-2, 21, 28, 33, 102, 103, 125, 130, 140, 142 and 222 were significantly superior over DS-28 (14.28 μmol CO₂ m_-2 sec_-1) 2 for photosynthetic rate. It indicates the possibility of improvement in physiological, yield and fibre quality traits of G. hirsutum L. cotton through interspecific hybridization in tetraploid cotton.